Other Current Assets - Summary of Other Current Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Prepaid Expense And Other Assets Current [Abstract]
Restricted cash of subsidiaries	$ 86	$ 56
Sales and use tax receivables	41	48
Prepaid expenses	21	15
Prepaid incentives	17	18
Assets held for sale	16	16
Derivative assets	2	10
Other	13	7
Other current assets, Total	$ 196	$ 170